[5] In the 1930s and 1940s zoologist Ivan Buresh and his associate Yordan Tsonkov conducted in-depth research on the diversity and distribution of the amphibian and reptile species in the country.
The country has a dense network of rivers but with the notable exception of the Danube, they are mostly short and with low water flow.
Most species have slightly toxic skin secretions and many develop dorsal body and tail fins when they return to an aquatic stage.
Bufonidae include the typical toads with shortened forelimbs, hindlimbs used for walking or hopping, dry warty skin, and parotoid glands behind eyes.
Hylids range from small to large in size and usually have distinct adhesive toe discs that contain a cartilage offsetting the terminal phalanx, which aids in climbing.
[31] Pelobatidae, also known as spadefoot toads, are a small family of frogs with one genus and four species spread in Europe, Western Asia and North-western Africa.
They have short legs, stocky bodies with vertical pupils and produce an odour similar to garlic, hence their name in Bulgarian is чесновица (chesnovica), 'garlic toad'.